Notch inhibition reduces cell size. (A) The indicated cell lines were treated with GSI (compound E) or vehicle (DMSO) for 7 days. After the incubation period, relative size (forward scatter) of G₀/G₁-gated cells was determined by flow cytometry. Histograms with FSC on the X-axis are shown. (B) The magnitude of size reduction for each of the 13 tested lines was measured after exposure to GSI for 7 days and correlated with its corresponding suppression in p70 S6 kinase (T389) phosphorylation as measured using RPP microarrays. Size of GSI-treated cells is reported as a percentage of mock (DMSO)–treated cells on the X-axis. The level of phospho-p70 S6 kinase (T389) is shown on the Y-axis as the median-centered log₂ ratio of GSI/DMSO-treated cells.